Iontophoresis is a needle-free, non-invasive technology for delivering nutrients, medicines, vitamins, minerals, therapeutic agents, drugs or other bioactive agents through the skin using a small electric current. These beneficial bioactive agents are referred to herein generally as medicaments. In general, delivering such medicaments through iontophoresis involves applying an electromotive force that transports ions through the stratum corneum, the outermost layer of skin, and into the dermis, the inner layer of skin that is comprised of connective tissue, blood and lymph vessels, sweat glands, hair follicles and an elaborate sensory nerve network.
Iontophoresis has proven effective for many treatments. For example, iontophoresis can be used to drive pilocarpine across the skin barrier to stimulate sweating in the sweat chloride test for cystic fibrosis. Alternatively, iontophoresis can be reversed to draw a molecule such as glucose out through the skin, for example to measure blood glucose levels in diabetic patients. Ionotophoresis is also commonly used with anti-inflammatory medications and to treat many common illnesses, such as plantar fascitis, bursitis and hyperhidrosis. Iontophoresis can also be used to deliver genes, detoxify patients, reduce pain, or deliver nutrition into a patient's body. Examples of positively charged ions that can be driven into the skin by an iontophoresis device include zinc, copper, alkaloids, certain anesthetics, and certain vasodilating drugs. Examples of negatively charged ions that can be driven into the skin by an iontophoresis device include salicylate, fluoride, penicillin and insulin.
Compared to popular methods of delivering drugs, such as local skin patches, injections, or oral delivery, there are significant advantages to delivering medicaments through iontophoresis. First, compared to local skin patches, using iontophoresis enhances the skin's permeability, allowing for greater faster drug delivery, higher dose rates, and shorter treatment times. Second, compared to hypodermic injection, iontophoresis is non-invasive thereby increasing patient compliance, avoiding painful injections, and reducing the associated risk of infections. Finally, even compared to oral delivery of medications, iontophoresis has advantages. When medications are administered orally, they must pass through the digestive tract where absorption can vary significantly from individual to individual. Moreover, when taken orally, the drug must pass through the liver where it is not unusual for a significant amount of the drug to be inactivated. Iontophoretic delivery on the other hand allows a medicament to be absorbed in the circulatory system quickly, more reliably, and without patient discomfort or noncompliance.
Iontophoresis has historically been practiced by positioning two electrodes, an anode and a cathode, at some distance from each other on a patient and applying a low voltage between them for a long period of time. As a result, the charged atoms or molecules are transported actively by the force of the applied electrical field. Positively charged ions are driven into the skin at the anode while negatively charged ions are driven into the skin at the cathode. Regardless of the charge on the medicament, two electrodes are used in conjunction with the patient's skin to form a closed circuit that allows the flow of current between the electrodes. These traditional iontophoretic techniques have drawbacks. For example, one typical iontophoresis devices involve two electrodes, each with a patch or other surface for retaining a small amount of solution or gel containing a medicament. The electrodes and gel are placed on a patient's body at a distance apart, depending on where treatment is needed. Often a patient may feel discomfort or experience redness or burns where the electrode contacts the skin.
Another conventional iontophoresis device uses a reservoir for submerging a body part and the current is passed through the liquid in the reservoir. These devices suffer potential electrical shock hazard and severe overheating. Because standard AC current powers the devices during treatment, there is some risk that the patient would be shocked as a result of transient current spikes. The overheating is caused, in part, by high levels of salts or minerals in the water. These salts and minerals dissolve into their constituent ions, which increase the flow of current through the electrodes to an unsustainable level as the treatment proceeds. Elaborate fans and other moving parts have been devised to dissipate the heat.
Early devices also had no ability to choose from more than one electrode and no control over the duration, polarity or intensity of the treatment, other than to pull the plug from the power supply. Thus, a treatment was limited to one type of electrode and limited in duration and control. Additionally, the devices burned out frequently. The current and voltage spikes common to commercial AC power supplies exacerbated the burnout problem.
Therefore, it is an object of this invention to provide an iontophoresis device for with improved safety and convenience. It is also an object of this invention to provide a device for iontophoresis that reduces the potential electrical shock hazard and the potential for burns. It is another object to provide a device that does not overheat under normal operation. It is a further object to provide a device that has control over the duration, polarity and intensity of the treatment and allows the user to easily choose the most appropriate electrode for his purpose.